The primary objective of this study is to conduct descriptive analyses of GBACR data linked to Medicare claims data; to share the results with the SEER working groups and NCI; to work closely with the SEER working groups and NCI to develop and implement algorithms that could be applied to SEER-Medicare data to identify cases that had received radiation, chemotherapy, or hormone therapy (for prostate cancer); and to define the process for routinely incorporating additional information into the existing SEER treatment variables. The methods developed shall enhance the Registrys ability to identify cases that may be missing chemotherapy, radiation, and hormone treatment information in the registry database.